Study on Natural Convection around a vertical heated rod using PIV/LIF technique
20th Symposium of AER on VVER Reactor Physics and Reactor Safety (2010, Hanasaari, Espoo, Finland)
Nuclear applications of three-dimensional thermal hydraulics
Abstract
The Nuclear Training Reactor of the Institute of Nuclear Techniques (Budapest
University of Technology and Economics, Hungary) is a pool-type reactor with light water
moderator and with a maximum thermal power of 100 kW. The fuel elements are cooled by
natural convection. An experimental setup was built to analyse the nature of the natural
convection around a heated rod. The flow field was investigated using an electrically heated
rod, which models the geometry of a fuel pin in the training reactor. The electric power of the
model rod is variable between 0?500 W. The rod was placed in a square-based glass tank.
PIV (Particle Image Velocimetry) and LIF (Laser Induced Fluorescence) measurement
techniques were used to study the velocity and temperature field in a two-dimensional area.
The thermal and the hydraulic boundary layers were detected near a rod in a lower
section of the aquarium. The laminar-turbulent transition of the flow regime was observed,
the maximum velocity of the up-flow was 0.025-0.05 m/s. From the temperature
measurements the local heat transfer coefficient was estimated.